[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] Multiple IRQ's in HVM for Windows
> On 27/12/2008 10:28, "James Harper" <james.harper@xxxxxxxxxxxxxxxx> wrote: > > > Well... the 'old' way would probably still have to work (or would it?), > > so we could just keep allocating IRQ's until we run out and any leftover > > devices just have to use the old way. > > Yes, that did occur to me. Might be a nice fallback while still allowing > up to 16 or whatever devices to have their interrupts distributed across > VCPUs. > The old mechanism does still need to work, so making it a fallback in this > new mechanism would be probably not too difficult. Is Windows limited to 31 IRQ's? Linux appears to allow much more than that, but maybe I'm not comparing apples with apples here. Still... an average Windows system under Xen would have a few disks, a few network adapters, and maybe a scsi passthrough. I think it would be unusual to see a requirement for more than 6 IRQ's, so I don't think that a limit of 16 is going to cripple anyone. So are you suggesting that these interrupts be non-shareable? Would that remove the need to check for a pending interrupt status in Xen, and for the virtual device driver to clear any flags? > > > I've mentioned the possibility of using MSI before... would that work? > > I'm not yet sure if they are supported across all windows versions, but > > we get lots more 'interrupt channels'... > > Well, would Windows need to see more fake PCI devices (where these MSIs > would emanate from) for this to work? It would be nice, though perhaps not > essential, to avoid this since it needs backwards-compatible changes to > qemu-dm, and also possibly our vBIOS. > Unfortunately I don't know enough about MSI and how Windows handles MSI to be able to answer that. Lets give it a miss :) James _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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